Public Information Statement
Issued by NWS National HQ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
NOUS41 KWBC 271955 AAA

Service Change Notice 17-17 Updated
National Weather Service Headquarters Silver Spring, MD
355 PM EDT Mon Mar 27 2017

To:   Subscribers:
     -NOAA Weather Wire Service
     -Emergency Managers Weather Information Network
     Other NWS Partners and Employees

From:  Dave Myrick
      NWS Office of Science and Technology Integration

Subject: Updated:  RTMA and URMA Upgrade: Effective May 2, 2017

Updated to change implementation date to Tuesday, May 2, 2017

Effective on or about Tuesday, May 2, 2017, beginning with the
1500 Universal Coordinated Time (UTC) cycle, the National
Centers for Environmental Prediction (NCEP) will upgrade the
Real-Time Mesoscale Analysis (RTMA) and the Unrestricted
Mesoscale Analysis (URMA) as follows:

- Changes to model components
- Addition of new product fields, including onto NOAAPORT
- Product output changes

1) Model Changes

A. The following changes are made for RTMA-CONUS and URMA-CONUS
a) Expand the domain westward by 200 columns (approximately 500
b) Change the background field for the cloud ceiling height
analysis from downscaled RAP forecast to downscaled HRRR
forecast. The downscaled RAP is only retained along the edges of
the domain which are not covered by the HRRR.
c) Update the accept list for the wind direction-based
observation quality control
d) Change the background field for visibility in Alaska from a
downscaled NAM forecast to a downscaled 1-hour RAP forecast.

The expansion of the CONUS domain is in response to a request
from the Ocean Prediction Center. It also benefits the western
WFOs and the National Blend Project. It should be noted that
products for the smaller NDFD CONUS grid and Northwest River
Forecast Center grid will continue to be disseminated as before.
The use of the 3-km HRRR model to provide the background for
cloud ceiling represents an upgrade over the use of the coarser
13-km RAP model. The updated wind direction-based observation
accept list reflects the most recent wind statistics from the
HRRR model used to provide the background for the wind analysis.
Using the RAP (rather than NAM) forecast to generate the
background for visibility for Alaska allows the use of a
shorter-term forecast (1 hour with RAP, up to 6 hours with NAM).
This also makes the RAP the primary background model used to
generate the background field over Alaska for all variables.

B. The following changes are made for the NCEP Stage IV:
a) NCEP is adding Alaska (AK) and Puerto Rico (PR) QPE`s to the
Stage IV/URMA.The AK Stage IV is 6h/24h, the PR Stage IV is
1h/6h/24h. The 6-hourly AK and PR Stage IV files are made into
precipitation URMA by mapping them from the River Forecast
Centers` local 4.7km polarstereographic grids to the AK NDFD
grid (3km polarstereographic) and the PR NDFD grid (2.5km
Mercator).  The AK/PR Stage IV/URMAs are made/remade within an
hour (at xxhr:33mn hourly run time) of QPE transmission from
RFCs to NCEP, and a final re-run is made 7 days (i.e. 168hr33mn)
after validation time.

Note on AK Stage IV/URMA: due to the severe lack of reliable
precipitation observations in Alaska, especially in winter, this
QPE is considered "qualitative" and should be used with caution.

b) The CONUS Stage IV 24h (12Z-12Z) will be mosaiced directly
from 24h QPEs from Northwest River Forecast Center (NWRFC) and
Missouri Basin River Forecast Center (MBRFC, falling back to 6h
QPE when an 24h QPE is unavailable), 6h QPE from CB and CN RFCs,
and 1h QPE from the other 8 central/eastern RFCs.  The 24h
mosaic will be made/remade hourly at each run cycle from 12:33
to 23:33Z after the day`s validation time (12Z), then re-made at
1/3/5/7-days after validation time (at the 12:33Z run).
Currently the 24h Stage IV is a simple sum of the 6h Stage IV
made at 15:33/21:33/23:33Z after the ending 12Z, then remade at
12:33Z 1/3/5/7 days later.  This is in support of the NWS AHPS -
the 24h mosaic will serve as precipitation source for

2) Changes on web services

The following web sites host data:

a) All precipitation analysis data will be moving from its
current location of
hourly/prod/nam_pcpn_anal.YYYYMMDD -->
  Where YYYY=4 digit year, MM=2 digit month, DD=2 digit day

b) New precipitation analysis files for Alaska and Puerto Rico
will be available under the new location:
 - Stage IV precipitation analysis output
 - Gif images of the Stage IV precipitation analysis output
 - Precipitation URMA files, mapped from Stage IV to NDFD grids
   Where XX=[01|06|24] for PR, [06|24] for AK, and HH=2 digit
   These files will be available as follows:
-    01h every hour
-    06h when HH=00, 06, 12, and 18
-    24h when HH=12

c) The following cloud ceiling files will be removed, and their
contents combined into existing files as noted.

From pub/data/nccf/com/rtma/prod/rtma2p5.YYYYMMDD remove:
and its contents, cloud ceiling (CEIL), will move into:

From pub/data/nccf/com/urma/prod/urma.YYYYMMDD remove:
and its contents, cloud ceiling (CEIL), will move into:

3) Additional URMA products over NOAAPORT/SBN
Total precipitation over Alaska and Puerto Rico will be added
where the WMO header information will be as follows:

T1T2A1A2ii cccc
 - cccc is KWBR
 where R is Real Time Mesoscale Analysis / Analysis of Error
 - T1 = L for forecast hours: A=00
 - T2 specifies parameter as follows:
     E - Total Precipitation
 - A1 specifies the grid ID as follows:
     C  - grid 195 URMA 2.5 km  (Puerto Rico)
     K  - grid  91 URMA 3.0 km (Alaska)
 - A2 specifies the forecast hour as follows:
     A=00  (Analysis)
 - ii specifies level as follows:
     98 = Surface

The WMO headers for Alaska and Puerto Rico are:
 Alaska is    LEKA98   KWBR
 Puerto Rico is    LECA98   KWBR

4) Product output changes
a) As noted above, cloud ceiling (CEIL) will be added to the
following files:
- rtma2p5.tHHz.[2dvaranl|2dvarerr]_[ndfd|nwrfc].grb2
- urma2p5.tHHz.[2dvaranl|2dvarerr]_[ndfd|nwrfc].grb2

Real-time sample parallel data for the RTMA/URMA is available
via the following URLs:

Real-time sample parallel data for the precipitation analysis is
available here:

More information about the RTMA and URMA update is available at:
Parallel RTMA:
Parallel URMA:
Operational RTMA:
Opera?ional URMA:
Parallel vs. Ops RTMA:
Parallel vs. Ops URMA:

Any questions, comments or requests regarding this
implementation should be directed to the contacts below. We will
review any feedback and decide whether to proceed.

For questions regarding these changes, please contact:

   John Derber
   NCEP/EMC Mesoscale Modeling Branch
   College Park, Maryland

For questions regarding the data flow aspects of these data
sets, please contact:

   Carissa Klemmer
   NCEP/NCO Dataflow Team
   College Park, Maryland

NWS National Service Change Notices are online at: is the U.S. government's official web portal to all federal, state and local government web resources and services.